Journal article
Erythropoietin protects the inner blood-retinal barrier by inhibiting microglia phagocytosis via Src/Akt/cofilin signalling in experimental diabetic retinopathy
Diabetologia, v 64(1), pp 211-225
Jan 2021
PMID: 33104828
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
Microglial activation in diabetic retinopathy and the protective effect of erythropoietin (EPO) have been extensively studied. However, the regulation of microglia in the retina and its relationship to inner blood-retinal barrier (iBRB) maintenance have not been fully characterised. In this study, we investigated the role of microglia in iBRB breakdown in diabetic retinopathy and the protective effects of EPO in this context.
Male Sprague Dawley rats were injected intraperitoneally with streptozotocin (STZ) to establish the experimental model of diabetes. At 2 h after STZ injection, the right and left eyes were injected intravitreally with EPO (16 mU/eye, 2 μl) and an equivalent volume of normal saline (NaCl 154 mmol/l), respectively. The rats were killed at 2 or 8 weeks after diabetes onset. Microglia activation was detected by ionised calcium binding adaptor molecule (IBA)-1 immunolabelling. Leakage of the iBRB was evaluated by albumin staining and FITC-dextran permeability assay. BV
cells and primary rat microglia under hypoxic conditions were used to model microglial activation in diabetic retinopathy. Phagocytosis was examined by confocal microscopy in flat-mounted retina preparations and in microglia and endothelial cell cocultures. Protein levels of IBA-1, CD11b, complement component 1r (C1r), and Src/Akt/cofilin signalling pathway components were assessed by western blotting.
In diabetic rat retinas, phagocytosis of endothelial cells by activated microglia was observed at 8 weeks, resulting in an increased number of acellular capillaries (increased by 426.5%) and albumin leakage. Under hypoxic conditions, activated microglia transmigrated to the opposite membrane of the transwell, where they disrupted the endothelial cell monolayer by engulfing endothelial cells. The activation and phagocytic activity of microglia was blocked by intravitreal injection of EPO. In vitro, IBA-1, CD11b and C1r protein levels were increased by 50.9%, 170.0% and 135.5%, respectively, by hypoxia, whereas the phosphorylated proteins of Src/Akt/cofilin signalling pathway components were decreased by 74.2%, 47.8% and 39.7%, respectively, compared with the control; EPO treatment abrogated these changes.
In experimental diabetic retinopathy, activated microglia penetrate the basement membrane of the iBRB and engulf endothelial cells, leading to iBRB breakdown. EPO exerts a protective effect that preserves iBRB integrity via activation of Src/Akt/cofilin signalling in microglia, as demonstrated in vitro. These data support a causal role for activated microglia in iBRB breakdown and highlight the therapeutic potential of EPO for the treatment of diabetic retinopathy. Graphical abstract.
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- Title
- Erythropoietin protects the inner blood-retinal barrier by inhibiting microglia phagocytosis via Src/Akt/cofilin signalling in experimental diabetic retinopathy
- Creators
- Hai Xie - Tongji UniversityChaoyang Zhang - Tongji UniversityDandan Liu - Tongji UniversityQian Yang - Tongji UniversityLei Tang - Tongji UniversityTianqin Wang - Renji HospitalHaibin Tian - Tongji UniversityLixia Lu - Tongji UniversityJing-Ying Xu - Tongji UniversityFurong Gao - Tongji UniversityJuan Wang - Tongji UniversityCaixia Jin - Tongji UniversityWeiye Li - Drexel UniversityGuoxu Xu - Department of Ophthalmology, the Second Affiliated Hospital of Soochow University, Suzhou, ChinaGuo-Tong Xu - Second Affiliated Hospital of Soochow UniversityJingfa Zhang - Tongji University
- Publication Details
- Diabetologia, v 64(1), pp 211-225
- Publisher
- Springer Nature
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Ophthalmology [Historical]
- Web of Science ID
- WOS:000583943000001
- Scopus ID
- 2-s2.0-85094158928
- Other Identifier
- 991019167427904721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Endocrinology & Metabolism